Embodiments of the present invention generally relate to as instrumentation system for preparation for implantation of a metaphyseal and/or diaphyseal implant or augment. More particularly, but not exclusively, embodiments of the present invention relate to instrumentation that facilitates a degree of positional freedom in the placement of a metaphyseal and/or diaphyseal implant or augment relative to a inference axis.
Proper alignment of a replacement joint device, including components of the replacement joint device, often may at least assist in attaining optimal wear resistance and optimal performance of the implanted device. Yet, patient anatomical variations present challenges in properly aligning the implant device for each patient. For example, during implant construct of knee replacement joints, challenges may arise with fitting a patient's intramedullary geometry with an implant, such as, for example, an intramedullary stem, while also fitting both the external geometry with a condylar replacing implant and the metaphyseal and/or diaphyseal geometry with an associated implant or augment component. Moreover, the addition of a metaphyseal and/or diaphyseal implant or augment to an implant construct often impairs the ability to adjustably fit the implant to the patient and/or attain proper alignment for various components of the implant. Such difficulties may at times be attributed to the anatomy of the patient, the geometrical constraints of the implant, and/or constraints associated with the preparatory instrumentation. For example, geometrical constraints of the metaphyseal and/or diaphyseal implant or augment may include the inability of the implant to accommodate the placement or position of both the intramedullary stem and the condylar implant, which can attribute to difficulties in forming a junction mechanism for those, and possibly other, components of the implant.
Challenges associated with attaining proper alignment during implant construct that involves metaphyseal and/or diaphyseal implants or augments have, at times, been resolved by compromises in terms of the placement of at least some components of the implant device, such as, for example, the location of the condylar implant. Yet, such compromises can result in less than optimal bone coverage, which can potentially compromise loading of the construct to the cortical rim of the bone. Other compromises can include reducing the stem size in order to offset the stem position, with the area vacated by such offsetting being made up with cement. Yet, for various reasons, such compromises may already impact the life of the implant, including being associated with failures relating to subsidence, loosening, stress-shielding factors, and increased stresses on the implant device, among other failures.
Therefore, the integrity of the implant construct may be adversely impacted if the bone is not shaped, during implant surgery, to accommodate the positioning of augmenting implants at locations in which the implanted augments, such as, for example, stems, sleeves, and cones, among other augments, will not interfere with the articular component and/or other augmenting implants.